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<title>django教程day04</title><link href='https://fonts.loli.net/css?family=Open+Sans:400italic,700italic,700,400&subset=latin,latin-ext' rel='stylesheet' type='text/css' /><style type='text/css'>html {overflow-x: initial !important;}:root { --bg-color: #ffffff; --text-color: #333333; --select-text-bg-color: #B5D6FC; --select-text-font-color: auto; --monospace: 'Lucida Console',Consolas,'Courier',monospace; }
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code { text-align: left; }
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table tr th { border-bottom-width: 0px; }
video { max-width: 100%; display: block; margin: 0px auto; }
iframe { max-width: 100%; width: 100%; border: none; }
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:root {
    --side-bar-bg-color: #fafafa;
    --control-text-color: #777;
}

@include-when-export url(https://fonts.loli.net/css?family=Open+Sans:400italic,700italic,700,400&subset=latin,latin-ext);

html {
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}

body {
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    color: rgb(51, 51, 51);
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#write {
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  	margin: 0 auto;
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}
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#write > ol:first-child{
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a {
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}
h1,
h2,
h3,
h4,
h5,
h6 {
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    margin-top: 1rem;
    margin-bottom: 1rem;
    font-weight: bold;
    line-height: 1.4;
    cursor: text;
}
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h2:hover a.anchor,
h3:hover a.anchor,
h4:hover a.anchor,
h5:hover a.anchor,
h6:hover a.anchor {
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h1 code {
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h2 code {
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h6 tt,
h6 code {
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h1 {
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}
h2 {
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}
h3 {
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}
h4 {
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}
h5 {
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}
h6 {
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    color: #777;
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p,
blockquote,
ul,
ol,
dl,
table{
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}
li>ol,
li>ul {
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}
hr {
    height: 2px;
    padding: 0;
    margin: 16px 0;
    background-color: #e7e7e7;
    border: 0 none;
    overflow: hidden;
    box-sizing: content-box;
}

li p.first {
    display: inline-block;
}
ul,
ol {
    padding-left: 30px;
}
ul:first-child,
ol:first-child {
    margin-top: 0;
}
ul:last-child,
ol:last-child {
    margin-bottom: 0;
}
blockquote {
    border-left: 4px solid #dfe2e5;
    padding: 0 15px;
    color: #777777;
}
blockquote blockquote {
    padding-right: 0;
}
table {
    padding: 0;
    word-break: initial;
}
table tr {
    border-top: 1px solid #dfe2e5;
    margin: 0;
    padding: 0;
}
table tr:nth-child(2n),
thead {
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}
table tr th {
    font-weight: bold;
    border: 1px solid #dfe2e5;
    border-bottom: 0;
    text-align: left;
    margin: 0;
    padding: 6px 13px;
}
table tr td {
    border: 1px solid #dfe2e5;
    text-align: left;
    margin: 0;
    padding: 6px 13px;
}
table tr th:first-child,
table tr td:first-child {
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}
table tr th:last-child,
table tr td:last-child {
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}

.CodeMirror-lines {
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}

.code-tooltip {
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    border-top: 1px solid #eef2f2;
}

.md-fences,
code,
tt {
    border: 1px solid #e7eaed;
    background-color: #f8f8f8;
    border-radius: 3px;
    padding: 0;
    padding: 2px 4px 0px 4px;
    font-size: 0.9em;
}

code {
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    padding: 0 2px 0 2px;
}

.md-fences {
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    margin-top: 15px;
    padding-top: 8px;
    padding-bottom: 6px;
}


.md-task-list-item > input {
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}

@media print {
    html {
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<div  id='write'  class = 'is-mac'><h1><a name="%E3%80%8Adjango-web%E6%A1%86%E6%9E%B6%E6%95%99%E5%AD%A6%E7%AC%94%E8%AE%B0%E3%80%8B" class="md-header-anchor"></a><span>《Django Web框架教学笔记》</span></h1><ul><li><span>讲师: 魏明择</span></li><li><span>时间: 2019</span></li></ul><h2><a name="%E7%9B%AE%E5%BD%95" class="md-header-anchor"></a><span>目录</span></h2><div class='md-toc' mdtype='toc'><p class="md-toc-content"><span class="md-toc-item md-toc-h1" data-ref="n0"><a class="md-toc-inner" href="#%E3%80%8Adjango-web%E6%A1%86%E6%9E%B6%E6%95%99%E5%AD%A6%E7%AC%94%E8%AE%B0%E3%80%8B">《Django Web框架教学笔记》</a></span><span class="md-toc-item md-toc-h2" data-ref="n8"><a class="md-toc-inner" href="#%E7%9B%AE%E5%BD%95">目录</a></span><span class="md-toc-item md-toc-h4" data-ref="n11"><a class="md-toc-inner" href="#%E6%9F%A5%E8%AF%A2%E6%95%B0%E6%8D%AE">查询数据</a></span><span class="md-toc-item md-toc-h3" data-ref="n143"><a class="md-toc-inner" href="#%E5%AD%97%E6%AE%B5%E6%9F%A5%E6%89%BE">字段查找</a></span><span class="md-toc-item md-toc-h4" data-ref="n152"><a class="md-toc-inner" href="#%E6%9F%A5%E8%AF%A2%E8%B0%93%E8%AF%8D">查询谓词</a></span><span class="md-toc-item md-toc-h3" data-ref="n229"><a class="md-toc-inner" href="#%E4%BF%AE%E6%94%B9%E6%95%B0%E6%8D%AE%E8%AE%B0%E5%BD%95">修改数据记录</a></span><span class="md-toc-item md-toc-h3" data-ref="n289"><a class="md-toc-inner" href="#%E5%88%A0%E9%99%A4%E8%AE%B0%E5%BD%95">删除记录</a></span><span class="md-toc-item md-toc-h3" data-ref="n322"><a class="md-toc-inner" href="#%E8%81%9A%E5%90%88%E6%9F%A5%E8%AF%A2">聚合查询</a></span><span class="md-toc-item md-toc-h3" data-ref="n402"><a class="md-toc-inner" href="#f%E5%AF%B9%E8%B1%A1">F对象</a></span><span class="md-toc-item md-toc-h3" data-ref="n446"><a class="md-toc-inner" href="#q%E5%AF%B9%E8%B1%A1---q()">Q对象 - Q()</a></span><span class="md-toc-item md-toc-h3" data-ref="n479"><a class="md-toc-inner" href="#%E5%8E%9F%E7%94%9F%E7%9A%84%E6%95%B0%E6%8D%AE%E5%BA%93%E6%93%8D%E4%BD%9C%E6%96%B9%E6%B3%95">原生的数据库操作方法</a></span></p></div><h4><a name="%E6%9F%A5%E8%AF%A2%E6%95%B0%E6%8D%AE" class="md-header-anchor"></a><span>查询数据</span></h4><ul><li><p><span>数据库的查询需要使用管理器对象进行</span></p></li><li><p><span>通过 MyModel.objects 管理器方法调用查询接口</span></p><figure><table><thead><tr><th><span>方法</span></th><th><span>说明</span></th></tr></thead><tbody><tr><td><span>all()</span></td><td><span>查询全部记录,返回QuerySet查询对象</span></td></tr><tr><td><span>get()</span></td><td><span>查询符合条件的单一记录</span></td></tr><tr><td><span>filter()</span></td><td><span>查询符合条件的多条记录</span></td></tr><tr><td><span>exclude()</span></td><td><span>查询符合条件之外的全部记录</span></td></tr><tr><td><span>...</span></td><td>&nbsp;</td></tr></tbody></table></figure></li></ul><ol start='' ><li><p><span>all()方法</span></p><ul><li><p><span>方法: all()</span></p></li><li><p><span>用法: MyModel.objects.all()</span></p></li><li><p><span>作用: 查询MyModel实体中所有的数据</span></p><ul><li><p><span>等同于</span></p><ul><li><span>select * from tabel</span></li></ul></li></ul></li><li><p><span>返回值: QuerySet容器对象,内部存放 MyModel 实例</span></p></li><li><p><span>示例:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">bookstore</span> <span class="cm-keyword">import</span> <span class="cm-variable">models</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">books</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">all</span>()</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">for</span> <span class="cm-variable">book</span> <span class="cm-keyword">in</span> <span class="cm-variable">books</span>:</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-builtin">print</span>(<span class="cm-string">"书名"</span>, <span class="cm-variable">book</span>.<span class="cm-property">title</span>, <span class="cm-string">'出版社:'</span>, <span class="cm-variable">book</span>.<span class="cm-property">pub</span>)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 132px;"></div><div class="CodeMirror-gutters" style="display: none; height: 132px;"></div></div></div></pre></li></ul></li><li><p><span>在模型类中定义 </span><code>def __str__(self):</code><span> 方法可以将自定义默认的字符串</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">class</span> <span class="cm-def">Book</span>(<span class="cm-variable">models</span>.<span class="cm-property">Model</span>):</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-variable">title</span> = ...</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-property">def</span> <span class="cm-variable">__str__</span>(<span class="cm-variable-2">self</span>):</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-keyword">return</span> <span class="cm-string">"书名: %s, 出版社: %s, 定价: %s"</span> <span class="cm-operator">%</span> (<span class="cm-variable-2">self</span>.<span class="cm-property">title</span>, <span class="cm-variable-2">self</span>.<span class="cm-property">pub</span>, <span class="cm-variable-2">self</span>.<span class="cm-property">price</span>)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 132px;"></div><div class="CodeMirror-gutters" style="display: none; height: 132px;"></div></div></div></pre></li><li><p><span>查询返回指定列(字典表示)</span></p><ul><li><p><span>方法: values(&#39;列1&#39;, &#39;列2&#39;)</span></p></li><li><p><span>用法: MyModel.objects.values(...)</span></p></li><li><p><span>作用: 查询部分列的数据并返回</span></p><ul><li><span>select 列1,列2 from xxx</span></li></ul></li><li><p><span>返回值: QuerySet</span></p><ul><li><span>返回查询结果容器，容器内存字典，每个字典代表一条数据,</span></li><li><span>格式为: {&#39;列1&#39;: 值1, &#39;列2&#39;: 值2}</span></li></ul></li><li><p><span>示例:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">bookstore</span> <span class="cm-keyword">import</span> <span class="cm-variable">models</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">books</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">values</span>(<span class="cm-string">"title"</span>, <span class="cm-string">"pub"</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">for</span> <span class="cm-variable">book</span> <span class="cm-keyword">in</span> <span class="cm-variable">books</span>:</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-builtin">print</span>(<span class="cm-string">"书名"</span>, <span class="cm-variable">book</span>[<span class="cm-string">"title"</span>], <span class="cm-string">'出版社:'</span>, <span class="cm-variable">book</span>[<span class="cm-string">'pub'</span>])</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-builtin">print</span>(<span class="cm-string">"book="</span>, <span class="cm-variable">book</span>)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 176px;"></div><div class="CodeMirror-gutters" style="display: none; height: 176px;"></div></div></div></pre></li></ul></li><li><p><span>查询返回指定列（元组表示)</span></p><ul><li><p><span>方法:values_list(&#39;列1&#39;,&#39;列2&#39;)</span></p></li><li><p><span>用法:MyModel.objects.values_list(...)</span></p></li><li><p><span>作用:</span></p><ul><li><span>返回元组形式的查询结果</span></li></ul></li><li><p><span>返回值: QuerySet容器对象,内部存放 </span><code>元组</code></p><ul><li><span>会将查询出来的数据封装到元组中,再封装到查询集合QuerySet中</span></li></ul></li><li><p><span>示例:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">bookstore</span> <span class="cm-keyword">import</span> <span class="cm-variable">models</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">books</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">values_list</span>(<span class="cm-string">"title"</span>, <span class="cm-string">"pub"</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">for</span> <span class="cm-variable">book</span> <span class="cm-keyword">in</span> <span class="cm-variable">books</span>:</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-builtin">print</span>(<span class="cm-string">"book="</span>, <span class="cm-variable">book</span>) &nbsp;<span class="cm-comment"># ('Python', '清华大学出版社')...</span></span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 154px;"></div><div class="CodeMirror-gutters" style="display: none; height: 154px;"></div></div></div></pre></li></ul></li><li><p><span>排序查询</span></p><ul><li><p><span>方法:order_by</span></p></li><li><p><span>用法:MyModel.objects.order_by(&#39;-列&#39;,&#39;列&#39;)</span></p></li><li><p><span>作用:</span></p><ul><li><span>与all()方法不同，它会用SQL 语句的ORDER BY 子句对查询结果进行根据某个字段选择性的进行排序</span></li></ul></li><li><p><span>说明:</span></p></li><li><p><span>默认是按照升序排序,降序排序则需要在列前增加&#39;-&#39;表示</span></p></li><li><p><span>示例:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">bookstore</span> <span class="cm-keyword">import</span> <span class="cm-variable">models</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">books</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">order_by</span>(<span class="cm-string">"price"</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">for</span> <span class="cm-variable">book</span> <span class="cm-keyword">in</span> <span class="cm-variable">books</span>:</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-builtin">print</span>(<span class="cm-string">"书名:"</span>, <span class="cm-variable">book</span>.<span class="cm-property">title</span>, <span class="cm-string">'定价:'</span>, <span class="cm-variable">book</span>.<span class="cm-property">price</span>)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 154px;"></div><div class="CodeMirror-gutters" style="display: none; height: 154px;"></div></div></div></pre></li></ul></li><li><p><span>根据条件查询多条记录</span></p><ul><li><p><span>方法: filter(条件)</span></p></li><li><p><span>语法: </span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">MyModel</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-variable">属性1</span>=<span class="cm-variable">值1</span>, <span class="cm-variable">属性2</span>=<span class="cm-variable">值2</span>)</span></pre></div></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 44px;"></div><div class="CodeMirror-gutters" style="display: none; height: 44px;"></div></div></div></pre></li><li><p><span>返回值:</span></p><ul><li><span>QuerySet容器对象,内部存放 MyModel 实例</span></li></ul></li><li><p><span>说明:</span></p><ul><li><span>当多个属性在一起时为&quot;与&quot;关系，即当</span><code>Books.objects.filter(price=20, pub=&quot;清华大学出版社&quot;)</code><span> 返回定价为20 </span><code>且</code><span> 出版社为&quot;清华大学出版社&quot;的全部图书</span></li></ul></li><li><p><span>示例:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><span><span>​</span>x</span></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 查询书中出版社为"清华大学出版社"的图书</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">bookstore</span> <span class="cm-keyword">import</span> <span class="cm-variable">models</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">books</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-variable">pub</span>=<span class="cm-string">"清华大学出版社"</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">for</span> <span class="cm-variable">book</span> <span class="cm-keyword">in</span> <span class="cm-variable">books</span>:</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-builtin">print</span>(<span class="cm-string">"书名:"</span>, <span class="cm-variable">book</span>.<span class="cm-property">title</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span cm-text="">​</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-number">2.</span> <span class="cm-variable">查询Author实体中id为1并且isActive为True的</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-operator">-</span> <span class="cm-variable">authors</span>=<span class="cm-variable">Author</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-builtin">id</span>=<span class="cm-number">1</span>,<span class="cm-variable">isActive</span>=<span class="cm-keyword">True</span>)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 308px;"></div><div class="CodeMirror-gutters" style="display: none; height: 308px;"></div></div></div></pre></li></ul></li></ol><h3><a name="%E5%AD%97%E6%AE%B5%E6%9F%A5%E6%89%BE" class="md-header-anchor"></a><span>字段查找</span></h3><ul><li><p><span>字段查询是指如何指定SQL语句中 WHERE 子句的内容。</span></p></li><li><p><span>字段查询需要通过QuerySet的filter(), exclude() and get()的关键字参数指定。</span></p></li><li><p><span>非等值条件的构建,需要使用字段查询</span></p></li><li><p><span>示例:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 查询作者中年龄大于30</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">Author</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-variable">age__gt</span>=<span class="cm-number">30</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 对应</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># SELECT .... WHERE AGE &gt; 35;</span></span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 88px;"></div><div class="CodeMirror-gutters" style="display: none; height: 88px;"></div></div></div></pre></li></ul><h4><a name="%E6%9F%A5%E8%AF%A2%E8%B0%93%E8%AF%8D" class="md-header-anchor"></a><span>查询谓词</span></h4><ul><li><span>每一个查询谓词是一个独立的查询功能</span></li></ul><ol start='' ><li><p><code>__exact</code><span> : 等值匹配</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">Author</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-variable">id__exact</span>=<span class="cm-number">1</span>)</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 等同于select * from author where id = 1</span></span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 66px;"></div><div class="CodeMirror-gutters" style="display: none; height: 66px;"></div></div></div></pre></li><li><p><code>__contains</code><span> : 包含指定值</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">Author</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-variable">name__contains</span>=<span class="cm-string">'w'</span>)</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 等同于 select * from author where name like '%w%'</span></span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 88px;"></div><div class="CodeMirror-gutters" style="display: none; height: 88px;"></div></div></div></pre></li><li><p><code>__startswith</code><span> : 以 XXX 开始</span></p></li><li><p><code>__endswith</code><span> : 以 XXX 开始</span></p></li><li><p><code>__gt</code><span> : 大于指定值</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">Author</span>.<span class="cm-property">objects</span>.<span class="cm-property">filer</span>(<span class="cm-variable">age__gt</span>=<span class="cm-number">50</span>)</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 等同于 select * from author where age &gt; 50</span></span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 66px;"></div><div class="CodeMirror-gutters" style="display: none; height: 66px;"></div></div></div></pre></li><li><p><code>__gte</code><span> : 大于等于</span></p></li><li><p><code>__lt</code><span> : 小于</span></p></li><li><p><code>__lte</code><span> : 小于等于</span></p></li><li><p><code>__in</code><span> : 查找数据是否在指定范围内</span></p><ul><li><span>示例</span></li></ul><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">Author</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-variable">country__in</span>=[<span class="cm-string">'中国'</span>,<span class="cm-string">'日本'</span>,<span class="cm-string">'韩国'</span>])</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 等同于 select * from author where country in ('中国','日本','韩国')</span></span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 88px;"></div><div class="CodeMirror-gutters" style="display: none; height: 88px;"></div></div></div></pre></li><li><p><code>__range</code><span>: 查找数据是否在指定的区间范围内</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 查找年龄在某一区间内的所有作者</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">Author</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-variable">age__range</span>=(<span class="cm-number">35</span>,<span class="cm-number">50</span>))</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 等同于 SELECT ... WHERE Author BETWEEN 35 and 50;</span></span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 110px;"></div><div class="CodeMirror-gutters" style="display: none; height: 110px;"></div></div></div></pre></li><li><p><span>详细内容参见: </span><a href='https://docs.djangoproject.com/en/1.11/ref/models/querysets/#field-lookups' target='_blank' class='url'>https://docs.djangoproject.com/en/1.11/ref/models/querysets/#field-lookups</a></p></li></ol><ul><li><p><span>示例</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">MyModel</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-variable">id__gt</span>=<span class="cm-number">4</span>)</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 等同于 SELECT ... WHERE id &gt; 4;</span></span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 44px;"></div><div class="CodeMirror-gutters" style="display: none; height: 44px;"></div></div></div></pre></li><li><p><span>练习:</span></p><ol start='' ><li><p><span>查询Author表中age大于等于85的信息</span></p><ul><li><code>Author.objects.filter(age__gte=85)</code></li></ul></li><li><p><span>查询Author表中姓王的人的信息</span></p><ul><li><code>Author.objects.filter(name__startswith=&#39;王&#39;)</code></li></ul></li><li><p><span>查询Author表中Email中包含&quot;wc&quot;的人的信息</span></p><ul><li><code>Author.objects.filter(email__contains=&#39;wc&#39;)</code></li></ul></li></ol></li></ul><ol start='2' ><li><p><span>不等的条件筛选</span></p><ul><li><p><span>语法:</span>
<span>MyModel.objects.exclude(条件)</span></p></li><li><p><span>作用:</span></p><ul><li><span>返回不包含此 </span><code>条件</code><span> 的 全部的数据集</span></li></ul></li><li><p><span>示例:</span></p><ul><li><span>查询 </span><code>清华大学出版社，定价大于50</code><span> 以外的全部图书</span></li></ul><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">books</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">exclude</span>(<span class="cm-variable">pub</span>=<span class="cm-string">"清华大学出版社"</span>, <span class="cm-variable">price__gt</span>=<span class="cm-number">50</span>)</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">for</span> <span class="cm-variable">book</span> <span class="cm-keyword">in</span> <span class="cm-variable">books</span>:</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-builtin">print</span>(<span class="cm-variable">book</span>)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 110px;"></div><div class="CodeMirror-gutters" style="display: none; height: 110px;"></div></div></div></pre></li></ul></li><li><p><span>查询指定的一条数据</span></p><ul><li><p><span>语法:</span>
<span>MyModel.objects.get(条件)</span></p></li><li><p><span>作用：</span></p><ul><li><span>返回满足条件的唯一一条数据</span></li></ul></li><li><p><span>返回值:</span></p><ul><li><span>MyModel 对象</span></li></ul></li><li><p>&nbsp;</p></li><li><p><span>说明:</span></p><ul><li><span>该方法只能返回一条数据</span></li><li><span>查询结果多余一条数据则抛出,Model.MultipleObjectsReturned异常</span></li><li><span>查询结果如果没有数据则抛出Model.DoesNotExist异常</span></li></ul></li><li><p><span>示例:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">bookstore</span> <span class="cm-keyword">import</span> <span class="cm-variable">models</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">book</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">get</span>(<span class="cm-builtin">id</span>=<span class="cm-number">1</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-builtin">print</span>(<span class="cm-variable">book</span>.<span class="cm-property">title</span>)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 88px;"></div><div class="CodeMirror-gutters" style="display: none; height: 88px;"></div></div></div></pre></li></ul></li></ol><h3><a name="%E4%BF%AE%E6%94%B9%E6%95%B0%E6%8D%AE%E8%AE%B0%E5%BD%95" class="md-header-anchor"></a><span>修改数据记录</span></h3><ol start='' ><li><p><span>修改单个实体的某些字段值的步骤:</span></p><ol start='' ><li><p><span>查</span></p><ul><li><span>通过 get() 得到要修改的实体对象</span></li></ul></li><li><p><span>改</span></p><ul><li><span>通过 对象.属性 的方式修改数据</span></li></ul></li><li><p><span>保存</span></p><ul><li><span>通过 对象.save() 保存数据</span></li></ul></li></ol><ul><li><p><span>如:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">bookstore</span> <span class="cm-keyword">import</span> <span class="cm-variable">models</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">abook</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">get</span>(<span class="cm-builtin">id</span>=<span class="cm-number">10</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">abook</span>.<span class="cm-property">market_price</span> = <span class="cm-string">"10.5"</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">abook</span>.<span class="cm-property">save</span>()</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 110px;"></div><div class="CodeMirror-gutters" style="display: none; height: 110px;"></div></div></div></pre></li></ul></li><li><p><span>通过 QuerySet 批量修改 对应的全部字段</span></p><ul><li><p><span>直接调用QuerySet的update(属性=值) 实现批量修改</span></p></li><li><p><span>如:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 将 id大于3的所有图书价格定为0元</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">books</span> = <span class="cm-variable">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-variable">id__gt</span>=<span class="cm-number">3</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">books</span>.<span class="cm-property">update</span>(<span class="cm-variable">price</span>=<span class="cm-number">0</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 将所有书的零售价定为100元</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">books</span> = <span class="cm-variable">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">all</span>()</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">books</span>.<span class="cm-property">update</span>(<span class="cm-variable">market_price</span>=<span class="cm-number">100</span>)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 154px;"></div><div class="CodeMirror-gutters" style="display: none; height: 154px;"></div></div></div></pre></li></ul></li></ol><h3><a name="%E5%88%A0%E9%99%A4%E8%AE%B0%E5%BD%95" class="md-header-anchor"></a><span>删除记录</span></h3><ul><li><span>删除记录是指删除数据库中的一条或多条记录</span></li><li><span>删除单个MyModel对象或删除一个查询结果集(QuerySet)中的全部对象都是调用 delete()方法</span></li></ul><ol start='' ><li><p><span>删除单个对象</span></p><ul><li><p><span>步骤</span></p><ol start='' ><li><span>查找查询结果对应的一个数据对象</span></li><li><span>调用这个数据对象的delete()方法实现删除</span></li></ol></li><li><p><span>示例:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">try</span>:</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-variable">auth</span> = <span class="cm-variable">Author</span>.<span class="cm-property">objects</span>.<span class="cm-property">get</span>(<span class="cm-builtin">id</span>=<span class="cm-number">1</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-variable">auth</span>.<span class="cm-property">delete</span>()</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">except</span>:</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-builtin">print</span>(<span class="cm-variable">删除失败</span>)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 132px;"></div><div class="CodeMirror-gutters" style="display: none; height: 132px;"></div></div></div></pre></li></ul></li><li><p><span>删除查询结果集</span></p><ul><li><p><span>步骤</span></p><ol start='' ><li><span>查找查询结果集中满足条件的全部QuerySet查询集合对象</span></li><li><span>调用查询集合对象的delete()方法实现删除</span></li></ol></li><li><p><span>示例:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 删除全部作者中，年龄大于65的全部信息</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">auths</span> = <span class="cm-variable">Author</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-variable">age__gt</span>=<span class="cm-number">65</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">auths</span>.<span class="cm-property">delete</span>()</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 110px;"></div><div class="CodeMirror-gutters" style="display: none; height: 110px;"></div></div></div></pre></li></ul></li></ol><h3><a name="%E8%81%9A%E5%90%88%E6%9F%A5%E8%AF%A2" class="md-header-anchor"></a><span>聚合查询</span></h3><ul><li><span>聚合查询是指对一个数据表中的一个字段的数据进行部分或全部进行统计查询,查bookstore_book数据表中的全部书的平均价格，查询所有书的总个数等,都要使用聚合查询</span></li></ul><ol start='' ><li><p><span>不带分组聚合</span></p><ul><li><p><span>不带分组的聚合查询是指导将全部数据进行集中统计查询</span></p></li><li><p><span>聚合函数:</span></p><ul><li><p><span>定义模块: </span><code>django.db.models</code></p></li><li><p><span>用法: </span><code>from django.db.models import *</code></p></li><li><p><span>聚合函数: </span></p><ul><li><span>Sum, Avg, Count, Max, Min</span></li></ul></li></ul></li><li><p><span>语法: </span></p><ul><li><span>MyModel.objects.aggregate(结果变量名=聚合函数(&#39;列&#39;))</span></li></ul></li><li><p><span>返回结果:</span></p><ul><li><p><span>由 结果变量名和值组成的字典</span></p></li><li><p><span>格式为:</span></p><ul><li><span>`{&quot;结果变量名&quot;: 值}</span></li></ul></li></ul></li><li><p><span>示例:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 得到所有书的平均价格</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">bookstore</span> <span class="cm-keyword">import</span> <span class="cm-variable">models</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">django</span>.<span class="cm-property">db</span>.<span class="cm-property">models</span> <span class="cm-keyword">import</span> <span class="cm-variable">Count</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">result</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">aggregate</span>(<span class="cm-variable">myAvg</span>=<span class="cm-variable">Avg</span>(<span class="cm-string">'price'</span>))</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-builtin">print</span>(<span class="cm-string">"平均价格是:"</span>, <span class="cm-variable">result</span>[<span class="cm-string">'myAvg'</span>])</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-builtin">print</span>(<span class="cm-string">"result="</span>, <span class="cm-variable">result</span>) &nbsp;<span class="cm-comment"># {"myAvg": 58.2}</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span cm-text="">​</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 得到数据表里有多少本书</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">django</span>.<span class="cm-property">db</span>.<span class="cm-property">models</span> <span class="cm-keyword">import</span> <span class="cm-variable">Count</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">result</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">aggregate</span>(<span class="cm-variable">mycnt</span>=<span class="cm-variable">Count</span>(<span class="cm-string">'title'</span>))</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-builtin">print</span>(<span class="cm-string">"数据记录总个数是:"</span>, <span class="cm-variable">result</span>[<span class="cm-string">'mycnt'</span>])</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-builtin">print</span>(<span class="cm-string">"result="</span>, <span class="cm-variable">result</span>) &nbsp;<span class="cm-comment"># {"mycnt": 10}</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span cm-text="">​</span></span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 506px;"></div><div class="CodeMirror-gutters" style="display: none; height: 506px;"></div></div></div></pre></li></ul></li><li><p><span>分组聚合</span></p><ul><li><p><span>分组聚合是指通过计算查询结果中每一个对象所关联的对象集合，从而得出总计值(也可以是平均值或总和)，即为查询集的每一项生成聚合。</span></p></li><li><p><span>语法: </span></p><ul><li><span>QuerySet.annotate(结果变量名=聚合函数(&#39;列&#39;))</span></li></ul></li><li><p><span>用法步骤:</span></p><ol start='' ><li><p><span>通过先用查询结果MyModel.objects.value. 查找查询要分组聚合的列</span></p><ul><li><p><span>MyModel.objects.value(&#39;列1&#39;, &#39;列2&#39;)</span></p></li><li><p><span>如: </span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">pub_set</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">values</span>(<span class="cm-string">'pub'</span>)</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-builtin">print</span>(<span class="cm-variable">books</span>) &nbsp;<span class="cm-comment"># &lt;QuerySet [{'pub': '清华大学出版社'}, {'pub': '清华大学出版社'}, {'pub_hou {'pub': '机械工业出版社'}, {'pub': '清华大学出版社'}]&gt;</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span cm-text="">​</span></span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 220px;"></div><div class="CodeMirror-gutters" style="display: none; height: 220px;"></div></div></div></pre></li></ul></li><li><p><span>通过返回结果的 QuerySet.annotate 方法分组聚合得到分组结果</span></p><ul><li><p><span>QuerySet.annotate(名=聚合函数(&#39;列&#39;))</span></p></li><li><p><span>返回 QuerySet 结果集,内部存储结果的字典</span></p></li><li><p><span>如:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">pub_count_set</span> = <span class="cm-variable">pub_set</span>.<span class="cm-property">annotate</span>(<span class="cm-variable">myCount</span>=<span class="cm-variable">Count</span>(<span class="cm-string">'pub'</span>))</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-builtin">print</span>(<span class="cm-variable">pub_count_set</span>) &nbsp;<span class="cm-comment"># &lt;QuerySet [{'pub': '清华大学出版社', 'myCount': 7}, {'pub': '机械工业出版社', 'myCount': 3}]&gt;</span></span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 176px;"></div><div class="CodeMirror-gutters" style="display: none; height: 176px;"></div></div></div></pre></li></ul></li></ol><ul><li><span>.values(&#39;查询列名&#39;)</span></li></ul></li><li><p><span>示例:</span></p><ul><li><span>得到哪儿个出版社共出版多少本书</span></li></ul><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">def</span> <span class="cm-def">test_annotate</span>(<span class="cm-variable">request</span>):</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; <span class="cm-operator">-</span> <span class="cm-keyword">from</span> <span class="cm-variable">django</span>.<span class="cm-property">db</span>.<span class="cm-property">models</span> <span class="cm-keyword">import</span> <span class="cm-variable">Count</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> . <span class="cm-property">import</span> <span class="cm-variable">models</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span cm-text="">​</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-comment"># 得到所有出版社的查询集合QuerySet</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-variable">pub_set</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">values</span>(<span class="cm-string">'pub'</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-comment"># 根据出版社查询分组，出版社和Count的分组聚合查询集合</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-variable">pub_count_set</span> = <span class="cm-variable">pub_set</span>.<span class="cm-property">annotate</span>(<span class="cm-variable">myCount</span>=<span class="cm-variable">Count</span>(<span class="cm-string">'pub'</span>)) &nbsp;<span class="cm-comment"># 返回查询集合</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-keyword">for</span> <span class="cm-variable">item</span> <span class="cm-keyword">in</span> <span class="cm-variable">pub_count_set</span>:</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-builtin">print</span>(<span class="cm-string">"出版社:"</span>, <span class="cm-variable">item</span>[<span class="cm-string">'pub'</span>], <span class="cm-string">"图书有："</span>, <span class="cm-variable">item</span>[<span class="cm-string">'myCount'</span>])</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-keyword">return</span> <span class="cm-variable">HttpResponse</span>(<span class="cm-string">'请查看服务器端控制台获取结果'</span>)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 462px;"></div><div class="CodeMirror-gutters" style="display: none; height: 462px;"></div></div></div></pre></li></ul></li></ol><h3><a name="f%E5%AF%B9%E8%B1%A1" class="md-header-anchor"></a><span>F对象</span></h3><ul><li><span>一个F对象代表数据库中某条记录的字段的信息</span></li></ul><ol start='' ><li><p><span>作用:</span></p><ul><li><span>通常是对数据库中的字段值在不获取的情况下进行操作</span></li><li><span>用于类属性(字段)之间的比较。</span></li></ul></li><li><p><span>用法</span></p><ul><li><p><span>F对象在数据包 django.db.models 中，使用时需要先导入</span></p><ul><li><code>from django.db.models import F</code></li></ul></li></ul></li><li><p><span>语法:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">django</span>.<span class="cm-property">db</span>.<span class="cm-property">models</span> <span class="cm-keyword">import</span> <span class="cm-variable">F</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">F</span>(<span class="cm-string">'列名'</span>)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 44px;"></div><div class="CodeMirror-gutters" style="display: none; height: 44px;"></div></div></div></pre></li><li><p><span>说明:</span></p><ul><li><span>一个 F() 对象代表了一个model的字段的值</span></li><li><span>F对象通常是对数据库中的字段值在不加载到内存中的情况下直接在数据库服务器端进行操作</span></li></ul></li></ol><p>&nbsp;</p><ol start='5' ><li><p><span>示例1</span></p><ul><li><span>更新Book实例中所有的零售价涨10元</span></li></ul><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">all</span>().<span class="cm-property">update</span>(<span class="cm-variable">market_price</span>=<span class="cm-variable">F</span>(<span class="cm-string">'market_price'</span>)<span class="cm-operator">+</span><span class="cm-number">10</span>)</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 以下做法好于如下代码</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">books</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">all</span>()</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">for</span> <span class="cm-variable">book</span> <span class="cm-keyword">in</span> <span class="cm-variable">books</span>:</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-variable">book</span>.<span class="cm-property">update</span>(<span class="cm-variable">market_price</span>=<span class="cm-variable">book</span>.<span class="cm-property">marget_price</span><span class="cm-operator">+</span><span class="cm-number">10</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-variable">book</span>.<span class="cm-property">save</span>()</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 198px;"></div><div class="CodeMirror-gutters" style="display: none; height: 198px;"></div></div></div></pre></li><li><p><span>示例2</span></p><ul><li><span>对数据库中两个字段的值进行比较，列出哪儿些书的零售价高于定价?</span></li></ul><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">django</span>.<span class="cm-property">db</span>.<span class="cm-property">models</span> <span class="cm-keyword">import</span> <span class="cm-variable">F</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">bookstore</span> <span class="cm-keyword">import</span> <span class="cm-variable">models</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">books</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-variable">market_price__gt</span>=<span class="cm-variable">F</span>(<span class="cm-string">'price'</span>))</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">for</span> <span class="cm-variable">book</span> <span class="cm-keyword">in</span> <span class="cm-variable">books</span>:</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-builtin">print</span>(<span class="cm-variable">book</span>.<span class="cm-property">title</span>, <span class="cm-string">'定价:'</span>, <span class="cm-variable">book</span>.<span class="cm-property">price</span>, <span class="cm-string">'现价:'</span>, <span class="cm-variable">book</span>.<span class="cm-property">market_price</span>)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 198px;"></div><div class="CodeMirror-gutters" style="display: none; height: 198px;"></div></div></div></pre></li></ol><h3><a name="q%E5%AF%B9%E8%B1%A1---q()" class="md-header-anchor"></a><span>Q对象 - Q()</span></h3><ul><li><p><span>当在获取查询结果集 使用复杂的逻辑或  </span><code>|</code><span> 、 逻辑非 </span><code>~</code><span> 等操作时可以借助于 Q对象进行操作</span></p></li><li><p><span>如: 想找出定价低于20元 或 清华大学出版社的全部书，可以写成</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-variable">Q</span>(<span class="cm-variable">price__lt</span>=<span class="cm-number">20</span>)<span class="cm-operator">|</span><span class="cm-variable">Q</span>(<span class="cm-variable">pub</span>=<span class="cm-string">"清华大学出版社"</span>))</span></pre></div></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 44px;"></div><div class="CodeMirror-gutters" style="display: none; height: 44px;"></div></div></div></pre></li><li><p><span>Q对象在 数据包 django.db.models 中。需要先导入再使用</span></p><ul><li><code>from django.db.models import Q</code></li></ul></li></ul><ol start='' ><li><p><span>作用</span></p><ul><li><span>在条件中用来实现除 and(&amp;) 以外的 or(|) 或 not(~) 操作</span></li></ul></li><li><p><span>运算符:</span></p><ul><li><span>&amp; 与操作</span></li><li><span>| 或操作</span></li><li><span>〜 非操作</span></li></ul></li><li><p><span>语法</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">django</span>.<span class="cm-property">db</span>.<span class="cm-property">models</span> <span class="cm-keyword">import</span> <span class="cm-variable">Q</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">Q</span>(<span class="cm-variable">条件1</span>)<span class="cm-operator">|</span><span class="cm-variable">Q</span>(<span class="cm-variable">条件2</span>) &nbsp;<span class="cm-comment"># 条件1成立或条件2成立</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">Q</span>(<span class="cm-variable">条件1</span>)<span class="cm-operator">&amp;</span><span class="cm-variable">Q</span>(<span class="cm-variable">条件2</span>) &nbsp;<span class="cm-comment"># 条件1和条件2同时成立</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">Q</span>(<span class="cm-variable">条件1</span>)<span class="cm-operator">&amp;~</span><span class="cm-variable">Q</span>(<span class="cm-variable">条件2</span>) &nbsp;<span class="cm-comment"># 条件1成立且条件2不成立</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;">...</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 176px;"></div><div class="CodeMirror-gutters" style="display: none; height: 176px;"></div></div></div></pre></li><li><p><span>示例</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">django</span>.<span class="cm-property">db</span>.<span class="cm-property">models</span> <span class="cm-keyword">import</span> <span class="cm-variable">Q</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 查找清华大学出版社的书或价格低于50的书</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-variable">Q</span>(<span class="cm-variable">market_price__lt</span>=<span class="cm-number">50</span>) <span class="cm-operator">|</span> <span class="cm-variable">Q</span>(<span class="cm-variable">pub_house</span>=<span class="cm-string">'清华大学出版社'</span>))</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 查找不是机械工业出版社的书且价格低于50的书</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">filter</span>(<span class="cm-variable">Q</span>(<span class="cm-variable">market_price__lt</span>=<span class="cm-number">50</span>) <span class="cm-operator">&amp;</span> <span class="cm-operator">~</span><span class="cm-variable">Q</span>(<span class="cm-variable">pub_house</span>=<span class="cm-string">'机械工业出版社'</span>))</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 220px;"></div><div class="CodeMirror-gutters" style="display: none; height: 220px;"></div></div></div></pre></li></ol><h3><a name="%E5%8E%9F%E7%94%9F%E7%9A%84%E6%95%B0%E6%8D%AE%E5%BA%93%E6%93%8D%E4%BD%9C%E6%96%B9%E6%B3%95" class="md-header-anchor"></a><span>原生的数据库操作方法</span></h3><ul><li><p><span>使用MyModel.objects.raw()进行 数据库查询操作查询</span></p><ul><li><span>在django中，可以使用模型管理器的raw方法来执行select语句进行数据查询</span></li></ul><ol start='' ><li><p><span>语法: </span></p><ul><li><code>MyModel.objects.raw(sql语句)</code></li></ul></li><li><p><span>用法</span></p><ul><li><code>MyModel.objects.raw(&#39;sql语句&#39;)</code></li></ul></li><li><p><span>返回值:</span></p><ul><li><span>QuerySet 集合对象</span></li></ul></li></ol></li></ul><ol start='4' ><li><p><span>示例</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-variable">books</span> = <span class="cm-variable">models</span>.<span class="cm-property">Book</span>.<span class="cm-property">objects</span>.<span class="cm-property">raw</span>(<span class="cm-string">'select * from bookstore_book'</span>)</span></pre></div></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 66px;"></div><div class="CodeMirror-gutters" style="display: none; height: 66px;"></div></div></div></pre></li></ol><p><span>for book in books:</span>
<span>        print(book)</span>
<span>    ```</span></p><ul><li><p><span>使用django中的游标cursor对数据库进行 增删改操作</span></p><ul><li><p><span>在Django中可以使用 如UPDATE,DELETE等SQL语句对数据库进行操作。</span></p></li><li><p><span>在Django中使用上述非查询语句必须使用游标进行操作</span></p></li><li><p><span>使用步骤:</span></p><ol start='' ><li><p><span>导入cursor所在的包</span></p><ul><li><p><span>Django中的游标cursor定义在 django.db.connection包中，使用前需要先导入</span></p></li><li><p><span>如：</span></p><ul><li><code>from django.db import connection</code></li></ul></li></ul></li><li><p><span>用创建cursor类的构造函数创建cursor对象，再使用cursor对象,为保证在出现异常时能释放cursor资源,通常使用with语句进行创建操作</span></p><ul><li><p><span>如:</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation"><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">django</span>.<span class="cm-property">db</span> <span class="cm-keyword">import</span> <span class="cm-variable">connection</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">with</span> <span class="cm-variable">connection</span>.<span class="cm-property">cursor</span>() <span class="cm-keyword">as</span> <span class="cm-variable">cur</span>:</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-variable">cur</span>.<span class="cm-property">execute</span>(<span class="cm-string">'执行SQL语句'</span>)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 132px;"></div><div class="CodeMirror-gutters" style="display: none; height: 132px;"></div></div></div></pre></li></ul></li></ol><ul><li><p><span>示例</span></p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="python"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="python"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 8px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-comment"># 用SQL语句将id 为 10的 书的出版社改为 "XXX出版社"</span></span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">from</span> <span class="cm-variable">django</span>.<span class="cm-property">db</span> <span class="cm-keyword">import</span> <span class="cm-variable">connection</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">with</span> <span class="cm-variable">connection</span>.<span class="cm-property">cursor</span>() <span class="cm-keyword">as</span> <span class="cm-variable">cur</span>: </span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-variable">cur</span>.<span class="cm-property">execute</span>(<span class="cm-string">'update bookstore_book set pub_house="XXX出版社" where id=10;'</span>)</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span cm-text="">​</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">with</span> <span class="cm-variable">connection</span>.<span class="cm-property">cursor</span>() <span class="cm-keyword">as</span> <span class="cm-variable">cur</span>:</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-comment"># 删除 id为1的一条记录</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-variable">cur</span>.<span class="cm-property">execute</span>(<span class="cm-string">'delete from bookstore_book where id=10;'</span>)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom-width: 0px; border-bottom-style: solid; border-bottom-color: transparent; top: 352px;"></div><div class="CodeMirror-gutters" style="display: none; height: 352px;"></div></div></div></pre></li></ul></li></ul></li></ul><p>&nbsp;</p></div>
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